Method for manufacturing utensils and the like from the oxids of the rare earths, thorium oxid, zirconium oxid, and the like.



UNITED STATES PATENT OFFICE. f

HANS ARNOLD, CHARLOTTENBURG, GERMANY, ASSIGNOR TO THE FIRM 0F DR. 0

KNOFLEB & 00., OF PLOTZENSEE, NEAR BERLIN, GERMANY.

'METHOD FOR MANUFACTURING UTENSILS AND THE ,LIKE FROM THE OXTDS OF THE BARE EARTHS, THORIUM OXID, ZIRCONIUM OXID, AND THE'LIKE.

, Ho Drawing.

.a considerably higher fusing point than have china or clay-mixtures, quartz, alumini um oxld, and similar known mixtures and substances employed for the manufacture-of vessels and implements. Owing to that fact, various trials have been made to ema ploy the oxids of the rare earths, especially the zirconium oxid and the thorium oxid, for the article or articles in question. 'No practical result has, however, hitherto "been attained because the endeavors to Olzemz'c, '01. V65) found that an addition of v tures without fusion.

work the pure oxid.- without the addition of other substances or cementing media (whereby the fusing point of the composition is. considerably lowered) failed.

, Generally, the oxidsin-question, together with a cementing medium, have been turned into a paste. Weiss, who examined the conditions particularly with respect to zirco-= nium oxid (Zez'tschrift fair Anorgam'sche 10 0 of magnesia was necessary to produce crucibles that were able to stand burning. The zirconium crucibles existing in commerce also contain a large percentage of other components, which serve as cementing media and do not volatilize during the burning operation. These additions or, in fact, impurities lower, however, greatly, as already mentioned, the fusing pomt of the vessels or crucibles, so that these latter can only stand a temperatureof about 2000 C, whereas it is desirable that such vessels should be able to resist far higher tempera- It has now been found that a highly re fractory mass which is very well adapted for the manufacture ofvessels'by reason of Specification of Letters Patent.

solely in the employment of Patented'Dec. 22, 1914.

Application filed December 20, 1913. 5...... No. 808,013. 7

itsinherent plasticity. may be obtained by making use of the pure oxids, without any addition of another substance, except water.

If the vessels or implements are shaped in the usual manner by molding or castingand the articles thus produced are then burned,

1t w1ll be found thatthe shrinkage is very irregular and the articles are so porous'and their strength is so slight that they cannot practlcally be used. For example, it is not possible to glaze a vessel thus obtained after the burning since the molten glaze is absorbed simllarly as by a sponge and the glazing must be repeated four or five times before a'glazed coating is obtained. The material of the vessel or crucible is obviously rendered greatly impure in this way, with the result that by the lowering of the fusing point the vessels becomes useless for very high temperatures. Experiments have shown that this deficiency may be obviated by shaping the mass not by casting but by pressing. By this means the mass is rendered from the beginning so dense that the glaze cannot penetrate into it, but the first coating already remains upon the surface and the mass remains therefore pure. Thus,

according to the present invention, the oxids with each other by thepressure, in connection with the inherent plasticity of the oxids n The vesselsare then burned in question. in a known kiln at a temperature of about 16001800 C. and so get the necessary hard ness; they exhibitno cracks and no fissures, but consist of a uniform coherent compact mass of remarkable strength. "The shrinkage occurring'during the-burning ceases at about 1800-1900 C.

The gist of the invention resides thus not alone or solely in subjecting t e oxid. or

oxlds' to pressure, but itresides in the com- 100 pure oxids ticles of the oxid or mass being connected an oxid of another, or oxids of other rare earths.

In a variety of-cases itis desirable to have vessels which not only resist the high temperatures mentioned but are, moreover, impervious to fluxes and gases. Such crucibles are requiredfor instance for reducing and melting metals, viz: for keeping off, on one side, oxidizing gases, and on the other side, for keeping oii" carbonaceous gases which might render the metal impure by the formation of carbid or render it useless in another way, as would occur, for instance, with platinum.

Concerning the glazing of the vessels, it is obvious, that the fusing temperature of the glaze must be lower than that of the material of the vessel. It is known that small quantities of impurities lower the fusing point of the oxids considerably; in view of this, the glazing mass mayreceive an addition or additions of substances, such as titanium dioxid, aluminium oxid,silicic acid, and the like, in a definite quantity, or impure zirconium oxid may be employed from the beginning. By varying these additions oxid of a rare earth and water, subJecting and their quantities, mixtures with rising fusing points, corresponding to Segers fusing cones, may be produced, and the glaze may be'so chosen that its fusing point lies a few hundred degrees over the highest temperature which the vessel'or crucible will be exposed to-in actual use. The mixture se-- lected is turned into a thick paste by means of alcohol and the implements or utensils are coated with this paste. The coated article is then carefully dried and after this preliminaril burned at a temperature of about 800 whereby the coatmg or glaze receives the necessary strength. Then the temperature is raised until the glaze is in melting condition. According as acid or alkaline fluxes are employed in the preparation of the glaze,-the utensils or implements.

may be used also for rendering soluble ores of very difierent'kinds by acidor'basic substances. The. articles coated with such glazes are, even in the highest. temperatures, non-conductors or very bad conductors of electricity. This-is of very great practical yond 2000 C. can be produced solely by electric heating. Generally, a crucible of carbon inserted into the secondary circuit of a transformer is used. If impure oxids be employed as material for the formation of the crucible, this latter would become a conductor on being heated, the current would pass through the metal to be melted, the sectional area would become larger, the resistance less and the temperature would become lower. But owing to the present invention, in general and theglazes in question in particular, it is possible to render the crucible impervious without allowing it to become an electric conductor. Experiments have proved that it is possible to work for se eral hours running at temperatures over 3000 0., a result, that has generally been considered impossible up to the present. The possibility of manufacturing vessels and other utensils that may be regarded as practically perfectly refractory opens up new ways for carrying out many operations on a large scale, which could not hitherto be carried through. v

Having now described my invention, what I desire to secure by a patent of the United States is 1. The herein described method of manufacturing refractory utensils, which consists in forming a mixture consisting solely of the oxid of a rare earth and acompletely vaporizable medium capable of converting said oxid into a paste, subjecting said mixture to pressure to shape the same, and thereafter burning the resulting product.

2. The herein described method of manufacturing refractory utensils, which consists in forming a mixture containing solely the said mixture to pressure in a mold, whereby said mixture is shaped, and thereafter bur'n- "consisting in coating the utensils with" a glaze composed of thorium oxid, zirconium oxid, and an additional oxid, the quantit of said additional oxid being made depen ent upon the fusing point of the utensil to be produced, substantially and for the purpose as described.

5. The method of manufacturing refractory utensils from'the oxids of the rare earths, thorium oxid and zirconium oxid, consisting in subjecting the oxids or their mixture to pressure-in a mold, without any addition of other substances, such as a cementing medium or the like, except water,

coating the thus shaped utensils with a glaze composed of thorium oxid zirconium oxid, and additional oxid, the quantity of said additional oxid being made dependent upon the fusing point of the utens1l to be produced, and burning the thus shaped and glazed utensils, substantially and for thepurpose as deseribedl In testimon whereof I aflik my signature in presence 0 two witnesses.

p v HANS ARNOLD.

Witnesses: i

. WOLDEMAR HAUPT,

I'IENRY H'Asrm 

